arXiv subjects

Deok-Sun Lee

Publications and source records attributed to Deok-Sun Lee.

43 records · Page 3Linked to original sources

arXiv2005

Distribution of extremes in the fluctuations of two-dimensional equilibrium interfaces

We investigate the statistics of the maximal fluctuation of two-dimensional Gaussian interfaces. Its relation to the entropic repulsion between rigid walls and a confined interface is used to derive the average maximal fluctuation $ \sim \sqrt{2/(πK)} \ln N$ and the asymptotic behavior of the whole distribution $P(m) \sim N^2 e^{-{\rm (const)} N^2 e^{-\sqrt{2πK} m} - \sqrt{2πK} m}$ for $m$ finite with $N^2$ and $K$ the interface size and tension, respectively. The standardized form of $P(m)$ does not depend on $N$ or $K$, but shows a good agreement with Gumbel's first asymptote distribution with a particular non-integer parameter. The effects of the correlations among individual fluctuations on the extreme value statistics are discussed in our findings.

cond-mat.stat-mech↗

arXiv2005

Synchronization transition in scale-free networks: Clusters of synchrony

We study the synchronization transition in scale-free networks that display power-law asymptotic behaviors in their degree distributions. The critical coupling strength and the order-parameter critical exponent derived by the mean field approach depend on the degree exponent $λ$, which implies a close connection between structural organization and the emergence of dynamical order in complex systems. We also derive the finite-size scaling behavior of the order parameter finding that the giant cluster of synchronized nodes is formed in different ways between scale-free networks with $2<λ<3$ and those with $λ>3$.

cond-mat.stat-mech↗

arXiv2004

Collective roughening of elastic lines with hard core interaction in a disordered environment

We investigate by exact optimization methods the roughening of two and three-dimensional systems of elastic lines with point disorder and hard-core repulsion with open boundary conditions. In 2d we find logarithmic behavior whereas in 3d simple random walk-like behavior. The line 'forests' become asymptotically completely entangled as the system height is increased at fixed line density due to increasing line wandering.

cond-mat.dis-nn↗

arXiv2001

Two Dimensional Equilibrium Surface Roughness for Dissociative Dimer Dynamics

Equilibrium crystal surfaces, constrained to equilibrate by means of dissociative dimer deposition and evaporation, have anomalous global surface roughness. We generalize earlier results for one dimensional interfaces to two dimensions. The global surface width scales with surface size L as W^2 \sim log [L/ (log L)^{1/4}] instead of the conventional form W^2 \sim log L. The surface roughening transition does not change in nature, but its location is subject to a large and slowly varying logarithmic finite-size-scaling shift.

cond-mat.stat-mech↗

arXiv2001

Bethe Ansatz Solutions and Excitation Gap of the Attractive Bose-Hubbard Model

The energy gap between the ground state and the first excited state of the one-dimensional attractive Bose-Hubbard Hamiltonian is investigated in connection with directed polymers in random media. The excitation gap Δis obtained by exact diagonalization of the Hamiltonian in the two- and three-particle sectors and also by an exact Bethe Ansatz solution in the two-particle sector. The dynamic exponent z is found to be 2. However, in the intermediate range of the size L where UL~O(1), U being the attractive interaction, the effective dynamic exponent shows an anomalous peak reaching high values of 2.4 and 2.7 for the two- and the three-particle sectors, respectively. The anomalous behavior is related to a change in the sign of the first excited-state energy. In the two-particle sector, we use the Bethe Ansatz solution to obtain the effective dynamic exponent as a function of the scaling variable UL/π. The continuum version, the attractive delta-function Bose-gas Hamiltonian, is integrable by the Bethe Ansatz with suitable quantum numbers, the distributions of which are not known in general. Quantum numbers are proposed for the first excited state and are confirmed numerically for an arbitrary number of particles.

cond-mat.stat-mech↗

arXiv2000

Origin of the singular Bethe ansatz solutions for the Heisenberg XXZ spin chain

We investigate symmetry properties of the Bethe ansatz wave functions for the Heisenberg $XXZ$ spin chain. The $XXZ$ Hamiltonian commutes simultaneously with the shift operator $T$ and the lattice inversion operator $V$ in the space of $Ω=\pm 1$ with $Ω$ the eigenvalue of $T$. We show that the Bethe ansatz solutions with normalizable wave functions cannot be the eigenstates of $T$ and $V$ with quantum number $(Ω,Υ)=(\pm 1,\mp 1)$ where $Υ$ is the eigenvalue of $V$. Therefore the Bethe ansatz wave functions should be singular for nondegenerate eigenstates of the Hamiltonian with quantum number $(Ω,Υ)=(\pm 1,\mp 1)$. It is also shown that such states exist in any nontrivial down-spin number sector and that the number of them diverges exponentially with the chain length.

cond-mat.stat-mech↗

arXiv1999

Large Deviation Function of the Partially Asymmetric Exclusion Process

The large deviation function obtained recently by Derrida and Lebowitz for the totally asymmetric exclusion process is generalized to the partially asymmetric case in the scaling limit. The asymmetry parameter rescales the scaling variable in a simple way. The finite-size corrections to the universal scaling function and the universal cumulant ratio are also obtained to the leading order.

cond-mat.stat-mech↗